Conventionally, in order to search for data and/or services relating to a target article, a searcher enters a keyword relating to the article or makes a selection among the keywords presented by the system. This applies to the case where metadata representing the substance of a data and/or a service is registered in association with the base data beforehand and is used to search for the associated base data. Therefore, with such a keyword-based search system, there is a drawback in that it is sometimes difficult to select optimum keywords, i.e., the keywords for best narrowing down to the target data, since there may exist many keywords to be selected for searching for the target data especially at the initial stage of searching, resulting in insufficient searching.
Alternatively, an operating system which supports GUI (Graphical User Interface) such as Microsoft Windows (Registered Trademark) enables interaction between two objects by performing drag-and-drop on icons. The interaction includes moving a file into a folder and displaying data by using an application. The examples are disclosed in JP-A-11-53581 and JP-A-11-203835. In such conventional methods that cause interaction between two objects by means of drag-and-drop, the operation activated by the drag-and-drop is uniquely determined, allowing no selection by the user. In other words, with the drag-and-drop scheme in the conventional systems, when one or more data and/or programs are associated with each of one or more objects, it is not easy to select and execute any desired operation by combining such data and services each other and searching these combinations.